The primary change with GParted 0.28 is that it adds partial read-write support for LUKS-encrypted file-systems. GParted 0.28 is now able to copy/resize/manipulate file-systems within LUKS volumes as well as moving closed LUKS sub-volumes. However, this GNOME Partition Editor isn't yet able to create, open, or close LUKS encryption volumes.
GParted 0.28 also adds detection for the ISO9660 file-system as well as various bug-fixes. ISO9660 is the ISO standard for optical disc media and generally non-UDF ISO images.
More details on GParted 0.28 via the SourceForge project site.